Method and system for imaging a multi-pillar sample

Abstract

Methods include providing a multi-pillar sample including at least a first pillar and a second pillar parallel with the first pillar, directing a charged particle beam to the first pillar, imaging the first pillar at a plurality of rotational positions by rotating the multi-pillar sample about a first pillar axis of the first pillar, directing the charged particle beam to the second pillar, and imaging the second pillar at a plurality of rotational positions by rotating the multi-pillar sample about a second pillar axis of the second pillar. Related apparatus for performing disclosed methods are disclosed. Multi-pillar samples are also disclosed.

We claim: 
     
       1. A method, comprising:
 providing a multi-pillar sample including at least a first pillar and a second pillar parallel with the first pillar; 
 directing a charged particle beam to the first pillar; 
 imaging the first pillar at a plurality of rotational positions by rotating the multi-pillar sample about a first pillar axis of the first pillar; 
 directing the charged particle beam to the second pillar; and 
 imaging the second pillar at a plurality of rotational positions by rotating the multi-pillar sample about a second pillar axis of the second pillar. 
 
     
     
       2. The method of  claim 1 , further comprising reconstructing 3D images of the first pillar and the second pillar. 
     
     
       3. The method of  claim 2 , wherein the 3D images covering a full angular span of the first and the second pillar. 
     
     
       4. The method of  claim 1 , wherein a range of the plurality of positions is at least 170 degrees. 
     
     
       5. The method of  claim 1 , wherein a range of the plurality of positions is at least 80 degrees. 
     
     
       6. The method of  claim 1 , wherein a range of the plurality of positions is at least 180 degrees. 
     
     
       7. The method of  claim 1 , further comprising translating the multi-pillar sample along the first pillar axis and rotatably imaging another section of the first pillar before moving the multi-pillar sample to image the second pillar. 
     
     
       8. The method of  claim 1 , wherein imaging the first pillar includes rotating the multi-pillar sample to a selected position of either a +90 degree position or a −90 degree position and producing an image at the selected position with reduced obstruction by the second pillar or other pillars of the multi-pillar sample based on an angled linear arrangement of a plurality of pillars of the multi-pillar sample relative to a 0 degree position. 
     
     
       9. The method of  claim 1 , wherein the multi-pillar sample comprises a substrate defined by a length, a width, and a height, wherein the first pillar and the second pillar extend from the substrate along the height of the substrate and are arranged at different positions on the length of the substrate in a spaced series. 
     
     
       10. The method of  claim 9 , wherein the substrate is a sample carrier. 
     
     
       11. The method of  claim 9 , further comprising attaching a plurality of pillars to the substrate to form the multi-pillar sample. 
     
     
       12. The method of  claim 1 , wherein a distance between the first pillar and the second pillar is greater than 10 times of a diameter of either the first pillar or the second pillar. 
     
     
       13. The method of  claim 1 , further comprising directing a focused ion beam to mill a raw sample substrate to form the multi-pillar sample. 
     
     
       14. An apparatus, comprising:
 an imaging system configured to direct a charged particle beam to a multi-pillar sample including at least a first pillar and a second pillar; 
 a movement stage configured to move and rotate the multi-pillar sample about a plurality of different pillar axes of the multi-pillar sample; and 
 a processor and memory coupled to the sample stage and the imaging system wherein the memory includes code that, when executed by the processor: 
 causes the sample stage to rotate the multi-pillar sample about a first pillar axis of a first pillar, and to rotate the multi-pillar sample about a second pillar axis of the second pillar, and 
 causes the imaging system to direct the imaging beam through the first pillar at a plurality of rotational positions about the first pillar axis, and to direct the imaging beam through the second pillar at a plurality of rotational positions about the second pillar axis. 
 
     
     
       15. The apparatus of  claim 14 , further comprising an imaging sensor for detecting charged particles transmitted through the first pillar and the second pillar, and the memory includes further code that, when executed by the processor: causes the imaging sensor to detect a plurality of first images of the first pillar at the plurality of rotational positions about the first pillar axis, and detect a plurality of second images of the second pillar at the plurality of rotational positions about the second pillar axis. 
     
     
       16. The apparatus of  claim 14 , wherein the memory includes further code that, when executed by the processor: causes the processor to reconstruct 3D images of the first pillar and the second pillar based on the plurality of first images and the plurality of second images, respectively. 
     
     
       17. The apparatus of  claim 14 , wherein the multi-pillar sample comprises:
 a substrate defined by a length, a width, and a height, the substrate extending in a plane defined by the length and width; and 
 the first pillar and the second pillar extending parallel to each other from the substrate along the height of the substrate and arranged at different positions on the length of the substrate in a spaced series. 
 
     
     
       18. The apparatus of  claim 17 , further comprising a sample carrier, and the substrate is the sample carrier. 
     
     
       19. The apparatus of  claim 17 , wherein the first pillar axis and the second pillar axis form a pillar plane not parallel with a plane defined by the length and width of the substrate. 
     
     
       20. The apparatus of  claim 14 , wherein the memory includes further code that, when executed by the processor: causes the sample stage to move the multi-pillar sample so that the charged particle beam is directed to the first pillar or the second pillar. 
     
     
       21. The apparatus of  claim 14 , wherein the first pillar and the second pillar have a tip thickness of less than 400 nm, a base thickness of more than 400 nm, and a length of greater than 1 μm. 
     
     
       22. The apparatus of  claim 14 , wherein the first pillar and the second pillar have a tip thickness of less than 600 nm, a base thickness of more than 400 nm, and a length of greater than 1 μm.